In a particular application, the product is of the gel or cream type, for example for use in cosmetics or for pharmaceutical treatments.
Dispensing systems are known comprising a pump provided with a tube for feeding the product under pressure on which a push button is fixed in order to actuate the movement of said tube over a product-dispensing/aspiration travel.
In particular, the push button may comprise an actuation body having a product-ejection orifice and a sleeve having a well for mounting said push button on the feed tube of the pump. Thus, while pressing on the body of the push button, the pump is actuated in order to dispense the product in the form of a blob or a continuous stream.
Dispensing systems may be equipped with a means for reversible closure of the ejection orifice between two dispensings, in order to limit contacts between the external air and the product standing in the pump, in particular in order to avoid drying and/or degradation of said product over time.
To do this, the use of an elastically deformable valve is known, on which a movable lip is formed by applying the dispensing pressure to it. Reversible closure can then be obtained by arranging the valve on the body, with said lip in sealed contact in the ejection orifice, the movement of said lip opening said orifice.
However, the valves, which are components moulded separately and then attached to the body, have the drawback of low mechanical strength, that is to say they are sometimes carried away by the stream of product. In addition, in high-rate industrial productions, they are difficult to place on the body, since they consist of a material that is flexible and therefore often adherent to the walls of the feed chutes and the gripping members of the assembly machines.
According to another known embodiment, reversible closure can be obtained by means of a needle closing off the ejection orifice, said needle being movable between its positions of closing and opening said orifice over the actuation travel of the push button, in particular at the start of this travel. This embodiment has in particular the advantage of mechanically opening the ejection orifice without the product being pressurised to do this.
A push button is known from the document FR-2 948 343, comprising a needle closing the ejection orifice, in which the actuation body is slidably mounted about the sleeve between a high position and a low position forming between them a space for conveying the product from the mounting well to the ejection orifice. The needle is mounted between the body and the sleeve by means of a device for reversible movement between a closure position—or respectively an open position—when the body is in the high position—or respectively in the low position—, said push button also comprising a means of elastic return of the body to the high position.
In the embodiment described in this document, the elastic return means is formed by discontinuous lugs that extend between two rings of a member that is attached to the sleeve. Thus the sealing of the conveying space is achieved by sealed sliding of the sleeve in the body, which requires a dynamic seal that proves to be difficult to reproduce and may give rise to unpleasant friction in use.
In addition, the assembly of the five parts of the push button described in the document FR-2 948 343 proves to be difficult to implement at the rates imposed by the field of application.